dolphin remains (cetacea: odontoceti) from the middle miocene of

ACTA PALAEONTOLOGICA ROMANIAE V. 4 (2004), P. 179-189
DOLPHIN REMAINS (CETACEA: ODONTOCETI) FROM THE MIDDLE MIOCENE
OF CLUJ-NAPOCA, ROMANIA
EMESE KAZÁR1, MATEI VREMÍR2 & VLAD CODREA2
Abstract – Two incomplete dolphin skeletons and four ear bones from Sarmatian layers (Late Volhynian) of
the Iris Quarry in Cluj-Napoca were investigated. The fossil remains represent three individuals of the same
species. The humeri of both partial skeletons match the morphology of the holotype humerus of
Champsodelphis fuchsii BRANDT, 1873, a species in need of further taxonomic reconsideration. On the basis
of the petrosal morphology of the new material, Brandt’s species is tentatively placed in the genus Atocetus
MUIZON, 1988, family Kentriodontidae (Delphinoidea, Odontoceti). Our results show that Atocetus, hitherto
known from the eastern shoreline of the Pacific Ocean only, had Paratethyan occurrences as well.
Key words – Miocene, Sarmatian, Kentriodontidae, Atocetus, Champsodelphis fuchsii, Romania
INTRODUCTION
The fossil dolphin remains described in the
present paper were collected in the Iris Quarry of
Cluj-Napoca by Prof. J. A. P. Maxim in 1960-1965
and are being held in the Muzeul “Bazinul
Transilvaniei” (MBT) of the University Babeş-Bolyai
in Cluj-Napoca, Romania. The MBT 14943 and the
MBT 15029 specimens are partial skeletons of two
individuals, whereas the MBT 15001 consists of an
isolated left periotic and left tympanic, and a right
tympano-periotic complex. The latter elements were
described and assigned to as “Delphinoidea incertae
sedis (?Kentriodontidae)” by Codrea (1995), the
skeletons were preliminarily described and evaluated
by Kazár (2003).
The Iris Quarry is located in the northern part of
Cluj-Napoca, at the road leading to the village
Chinteni. Mészáros et al. (1991) presented a detailed
description of the geologic section exposed in the
quarry. The dolphin remains came from a layer of
calcareous marl above a thick layer of tuffs. The age
of the marls is Lower Sarmatian (Volhynian Stage,
Middle Miocene, NN 8; Mészáros et al., 1991).
MATERIAL & METHODS
In the present paper we describe the fossil
remains of three dolphin specimens of the MBT.
Comparisons were made with the holotypes and
referred specimens of several Miocene kentriodontid
species, but reference is given to the
phylogenetically closely related Atocetus nasalis
(BARNES, 1985) and Atocetus iquensis MUIZON,
1988 only. In the anatomical descriptions of the ear
bones we follow Fraser & Purves (1960), Kasuya
(1973), Barnes & Mitchell (1984), Muizon (1987) and
Luo & Marsh (1996). Terminology for the other
elements is mainly derived from Flower (1870), and
Rommel (1990). The measuring points of the arm
bones are figured in Kazár (2003) and Kazár &
Venczel (2003). All measurements were taken with
the same digital caliper.
1
2
Institutional abbreviations
MBT, Muzeul “Bazinul Transilvaniei”, University
“Babeş-Bolyai”, Cluj-Napoca; MNHN, Muséum
national d’Histoire naturelle, Paris; NHMW,
Naturhistorisches Museum Wien.
SYSTEMATIC PALEONTOLOGY
Cetacea BRISSON, 1762
Odontoceti FLOWER, 1869
Delphinida MUIZON, 1984
Delphinoidea GRAY, 1821
Kentriodontidae SLIJPER, 1936
Pithanodelphinae BARNES, 1985
Atocetus MUIZON, 1988
Atocetus(?) fuchsii (BRANDT, 1873)
1873a ?Champsodelphis Fuchsii J. F. Brandt – Brandt: pp.
269-276, pl. 29.
1873a Delphinus Fuchsii –Brandt: p. 275.
1873b Champsodelphis fuchsii –Brandt: p. 195.
1880 ?Champsodelphis Fuchsii –Van Beneden & Gervais:
p. 496.
1899 ?Acrodelphis Fuchsii Brandt sp.–Abel: p. 853.
1934 Acrodelphis fuchsii Brandt - Pia & Sickenberg: p. 37,
SK 287.
1937 Acrodelphis fuchsii – Pia: p. 403.
2003 Atocetus fuchsii (BRANDT, 1873) – Kazár: pp. 181189.
Holotype – NHMW 1859.XXVII.6.m, several
vertebrae, sternum, fragment of scapula, humerus
(Brandt, 1873a: pl. XXIX: figs. 1-7A).
Type locality and age – The holotype material
was found in the ”3. Ziegelgrube” in Nussdorf,
Vienna in 1859 (Brandt, 1873a). Brick quarries in
Nussdorf exposed clays of Sarmatian age (upper
Middle Miocene; e.g. Suess, 1862; Schmid, 1974).
Referred specimens from the Iris Quarry of
Cluj-Napoca, Romania – MBT 14943, partial
skeleton of eight thoracic vertebrae, both humeri, left
radius and ulna with almost complete manus, two
Geological Institute of Hungary, H-1143 Budapest, Stefánia út 14, E-mail: [email protected]
University Babeş-Bolyai, Str. M. Kogalniceanu nr. 1, 3400 Cluj-Napoca, Romania
179
E. KAZÁR, M. VREMÍR & V. CODREA
inassociated carpals and one phalanx, left scapula,
fragments of ribs and some unidentifyable fragments;
MBT 15001a, left periotic; MBT 15001b, left
tympanic; MBT 15001c, right tympano-periotic
complex of the same individual (Codrea, 1995); MBT
15029, partial skeleton containing right tympanoperiotic complex, fragments of mandible, atlas, axis,
the 7th and at least two other cervical vertebrae,
seven thoracic and two lumbar vertebrae, fragment
of left humerus, scapula and sternum.
Formation and age – Early Sarmatian
(Volhynian Stage, NN 8) according to Mészáros et al.
(1991).
Description of the Iris Quarry dolphin material
Skull and mandible – Possible skull fragments are
preserved with the MBT 14943 skeleton, but their
anatomical identification is difficult. The MBT 15029
specimen contains a mandible fragment. It was not
removed from the slab, now it exposes the lateral
surface of the postsymphyseal fragment of perhaps
the right ramus. The greatest depth (ca. 39 mm) was
measured at the posterior end of the preserved
fragment. Here, a slight concavity demarcates the
coronoid crest.
Periotic – The description of the petrosal bone is
based on the best preserved, from the tympanic
detached, MBT 15001/a periotic except where noted.
The overall shape of the periotic is elongate. The
cochlear part is low, it is tilted slightly anteriorly and
attaches to the body with a broad base. The internal
auditory meatus is narrow and continues
anterolaterally in a narrow slit. In the MBT 15001/b
periotic there is a low crest on the posteromedial
margin of the internal auditory meatus, the same
crest is absent in the MBT 15001/a and in the MBT
15029 periotics. Lateral to the internal auditory
meatus a dorsal flat area can be seen, which gives a
flat dorsal contour of the periotic in lateral view. The
perilymphatic foramen is situated at a relatively great
distance to the opening of the internal auditory
meatus and to the endolymphatic foramen. A
prominent eminence is present between the fenestra
rotunda and the foramen perilymphaticus. In the
ventral aspect of the periotic, the fossa for the head
of the malleus is large and medio-laterally elongated;
the ventrolateral tuberosity is strong.
The anterior process is short but not reduced in
size. In dorsal view it is triangular with a rounded tip,
projecting more anteriorly than medially. In medial
view, the dorsal angle of the anterior process
reaches farther anteriorly than the ventral angle in
the MBT 15001/b and the MBT 15029 periotics (the
dorsal angle is broken away in the MBT 15001/a
specimen). The posterior process is long with a
pentagonal articular surface, the tip of which can be
elongated in presumably old specimens (as in MBT
15001/a). In lateral view, the posterior process has a
straight dorsal margin, which closes at a wide angle
with the dorsal surface of the periotic. Measurements
of the MBT periotics are given in Table 1.
TABLE 1
Measurements of the periotics and tympanic bullae of Atocetus (?) fuchsii (BRANDT, 1873) from the Iris Quarry of ClujNapoca, Romania (in mm; e: estimated value; ?: missing data).
MBT
15001/a (left)
MBT
15001/c (left)
MBT
15029 (right)
periotic: total length from anterior tip of anterior
process to posterior tip of posterior process
27.5
29.3
25.5e
periotic: width across
ventrolateral tuberosity
16.7
16.3
16.5
12.5
13.1
12.5
and
3.5
3.9
3.2
periotic: distance between endolymphatic and
perilymphatic foramen
4.0
5.1
4.8
coxhlear
part
and
periotic: width across base of cochlear part
periotic:
distance
between
perilymphatic foramen
IAM
tympanic: length from anterior tip to posterior
end of inner posterior prominence
26.7
26.8
26.5e
tympanic: length from anterior tip to posterior
end of outer posterior prominence
28.8
28.6
28.5e
tympanic: depth between ventral margin and
top of sigmoid process
16.3
?
16.6
Tympanic – The description presented here is a
composite of the characteristics of all three
preserved tympanic bullae of the MBT material. All
are fragmentary; the lateral walls and the adjoining
180
MBT
15001/b
(right)
structures are crushed in the MBT 15001/b and in
the MBT 15029 tympanics, and of the MBT 15001/c
only the involucrum and both posterior eminences
are preserved.
DOLPHIN REMAINS (CETACEA: ODONTOCETI) FROM THE MIDDLE MIOCENE OF CLUJ-NAPOCA, ROMANIA
The involucrum is flattened and almost
completely smooth dorsally, with a sinusoid dorsal
contour. The inner and outer posterior prominences
are narrow, the inner being even more narrowed.
The outer posterior prominence projects farther
posteriorly than the inner. The median furrow is deep
and broad, it reaches to almost mid-length of the
ventral aspect of the tympanic bulla. The anterior lip
of the bulla is obtuse and there is no anterior spine.
The lateral wall of the bulla is relatively low; the
sigmoid process is bulbous and erect. The presence
or absence of the lateral furrow is unknown due to
the preservation state of all three specimens. For
measurements see Table 1.
Cervicals – Fragments of the atlas, axis and some of
the postaxial cervical vertebrae are preserved with
the MBT 15029 skeleton, whereas the centrum of the
7th cervical vertebra of the MBT 14943 can be
studied.
The atlas has broad triangular anterior articular
facets. The ventral lamina of the transverse process
is short, rounded off and it projects posterolaterally.
The neural canal is wider than that of Atocetus
iquensis. The axis has broad anterior articular facets.
The odontoid process is reduced, as is usual in the
Delphinoidea.
TABLE 2
Measurements of the 7th cervical and the preserved thoracic vertebrae of Atocetus(?) fuchsii from the Iris Quarry of ClujNapoca (in mm; ±0.5 mm; e: estimated value; ?: missing data. Ce: cervical vertebra; Th: thoracic vertebra). 1. length of
vertebral body; 2. width of vertebral body; 3. height of vertebral body.
Ce. 7th
Th. 1st
Th. 2nd
Th. 3rd
Th. 4th
Th. 5th
Th. 6th
Th. 7th
Th. 8th
Th. 9th
Th. 10th
MBT 14943
1.
6.0
8.0
10.0
14.0
17.5
?
21.0
24.5
27.5
?
31.0
2.
24.0e
30.0
23.5
22.5
21.5
?
19.5
20.0
21.0
?
20.5
3.
20.0
18.5
18.0
20.0
18.5
?
17.5
18.5
18.0
?
19.0
Thoracics – Of the thoracic region, vertebrae 1-4, 6-8
and 10 are preserved with the MBT 14943 skeleton.
All of their processes are broken away. The pedicles
of the neural arches tilt anteriorly and are positioned
anteriorly on the centra. The vertebral bodies are
shortened in thoracic vertebrae 1 through 4, the 6th
thoracic is cuboid, whereas the following ones have
slightly elongated centra. The vertebral epiphyses
are horizontally elliptical in the 1st thoracic, triangular
in the 2nd through 4th, and semicircular in the rest.
The MBT 15029 has thoracic vertebrae 1 through
7 preserved. They are basically similar to the
thoracics of the other skeleton. The 1st and 2nd
thoracics have horizontally elliptical epiphyses, the
following ones have semicircular epiphyses. The
spine of the second thoracic vertebra is partially
preserved; it is narrow and moderately tall, slightly
inclined posteriorly. The neural canal is wider than
high. Measurements of the thoracic vertebrae are
shown in Table 2.
Lumbars – Two incomplete lumbar vertebrae are
preserved with the MBT 15029 specimen, the
description is based on the better preserved one.
The vertebral body is slightly elongated (centrum
length: 26.5 mm; centrum width: 20.5 mm; centrum
height: 19.5 mm). The vertebral epiphyses are
circular, and in lateral view they are deflected from
MBT 15029
1.
5.5
5.5
7.5
16.5
18.5
21.0
?
26.5
?
?
?
2.
23.0
20.5
19.5
16.5
16.5
?
?
17.0
?
?
?
3.
17.0
16.0
14.0
15.0
15.0
?
?
16.0
?
?
?
the vertical plane. The lumbar arteries left a broad,
posteriorly opening V-shaped depression on the
ventral side of the lumbar vertebra, the ventral keel is
pronounced. The transverse process is long (43 mm)
and broad throughout its length, with a posterior (and
possibly anterior) extension from about midlength to
tip. This extension, however, is not triangular as in A.
iquensis but smoothly arched. The tip of the
transverse process is rounded off in ventral view.
Ribs – The preserved rib fragments of the MBT
15029 agree with the genral morphology of ribs in
delphinoids in their delicate, narrow and flattened
appearance.
Sternum – The sternum of MBT 15029 is exposed
with its dorsal side upward. Thus, the ventral surface
is unknown. The manubrium is incomplete with the
anterior processes and the lateral margins missing,
but the mesosternum is almost complete (Fig. 1). A
hollow area on the anterolateral part of the
manubrium indicates the attachment site of the first
pair of sternal ribs on either side. The mesosternum
is composed of two sternebrae. The first sternebra
almost equals the manubrium in length, whereas the
second is much shorter. The posterior margin of the
latter is hollowed out, forming a wide and relatively
deep posteior notch. The length of the sternum
between the deepest point of the anterior notch and
181
E. KAZÁR, M. VREMÍR & V. CODREA
the posterior notch is 68 mm. Minimal width across
the first sternebra is 29 mm, that of the second is
32 mm. The number of sternal ribs was probably 4
pairs.
Figure 1. Sternum of the MBT 15029 specimen of
Atocetus(?) fuchsii (BRANDT, 1873) from the Iris Quarry
of Cluj-Napoca in dorsal view. Scale bar: in cm.
Restoration (dotted line) is based on the holotype.
Scapula – An incomplete scapula is preserved
with both skeletons from the Iris Quarry. The
scapula of the MBT 14943 could be better
prepared and hence, the description is based on
this. In the present state of preservation, the
medial aspect of the left scapula can be studied.
The anterior margin and the acromion are not
preserved, and the anterior part of the dorsal
margin is covered by other elements. The distance
between the dorsal margin and the posterior
corner of the glenoid cavity is ca. 98 mm; the width
of the neck as preserved is 30 mm, and the length
of the glenoid cavity is 20.5 mm. The preserved
base of the coracoid process indicates that it was
a gracile process pointing anteriorly, similar to the
same element of A. iquensis. The posterior and
the dorsal margins close at an angle of about 60º
or less, which is very similar to A. iquensis.
Humerus – A distal fragment of the left
humerus is preserved with the MBT 15029, and
both humeri of MBT 14943. The description is
based on the best preserved left humerus of the
MBT 14943 skeleton. Comparative measurements
are presented in Table 3.
The humerus of Atocetus(?) fuchsii is reduced
in length in comparison with other Miocene
182
kentriodontids such as Delphinodon dividum
TRUE, 1912 and Incacetus broggii COLBERT,
1944, but not as compact and stout as in members
of the Delphinidae. There is a distinct neck region,
which is the narrowest portion of the bone in
lateral
view.
Distally
the
shaft
extends
anteroposteriorly, indicating large attachment site
for the deltoid muscle. The deltoid tuberosity is
distinct but not prominent, and it occupies the
distal half of the anterior margo. Nevertheless, it
does not reach the distal epiphysis. The
infraspinous fossa is moderately large, shallow
and it sits just below the caput, anterior to the
main axis of the shaft in lateral view. The caput is
relatively small (its dorsoventral depth takes up
about one-third of the humerus length) and is
slightly shifted laterally. The greater tubercule
forms a small but distinct plateau on the top of the
anterior margin of the humerus. The lesser
tubercule is mediolaterally broad with an elevated
posterior area. In anterior and posterior views the
humerus is not very robust but rather flat, where
the lesser tubercule extends medially from the
main axis of the bone. On the posterior margo, a
large articular surface indicates the presence of a
well-developed olecranon process of the ulna.
Radius and ulna –The lower arm is slightly
longer than the humerus. The radius is broader
than the ulna, and both lower arm bones are
mediolaterally flattened. The anterior margin of the
radius is convex, its posterior margin is slightly
concave. The ulna has straight anterior and
posterior margins, so that the narrow gap between
the radius and ulna has a semilunar outline. The
radius and ulna attach at their proximal and distals
ends, but a small articular facet for their
attachment is found at their proximal ends only.
The olecranon process of the ulna is well-defined,
flag-like.
Manus – The carpals are ordered in two distinct
rows. In the more proximal row, the scaphoid and
the cuneiform are relatively small and pentagonal,
whereas the lunar is very large and has a
trapezoid form. A small trapezium opens the
second row at the radial margin. This is followed
by the pentagonal trapezoid, which interdigitates
with the scaphoid and the lunar. The next carpal,
which interdigitates with the lunar and the
cuneiform, is probably the unciform. This means
that there is no magnum. The metacarpal I is small
and gracile, whereas the metacarpals II-V are
elongated, ca. 2-2.5 times longer than wide. The
proportions of the preserved phalanges are similar
to those of the metacarpals. The number of
phalanges is not clear, their probable arrangement
is 1-6-5-3-1.
DOLPHIN REMAINS (CETACEA: ODONTOCETI) FROM THE MIDDLE MIOCENE OF CLUJ-NAPOCA, ROMANIA
TABLE 3
Measurements of the humerus, radius and ulna of Atocetus(?) fuchsii from the Iris Quarry of Cluj-Napoca (in mm; ±0.5 mm;
?: missing data).
MBT 14943,
MBT 15029,
left
left
Length of the humerus
54.0
?
Anteroposterior diameter of the head of the humerus
19.5
?
Dorsoventral diameter of the head of the humerus
22.5
?
Mediolateral width of proximal epiphysis
30.0
?
Anteroposterior extension of the humerus neck
21.0
?
Mediolateral extension of the humerus neck
18.0
?
Anteroposterior extension of the distal epiphysis of the humerus
33.0
26.5
Mediolateral extension of the distal epiphysis of the humerus
14.5
12.5
Length of the radius
60.0
?
Anteroposterior extension of the proximal end of the radius
23.5
?
Anteroposterior extension of the distal end of the radius
29.5
?
Length of the ulna
53.5
?
Anteroposterior extension of the distal end of the ulna
28.0
?
DISCUSSION
In his monograph on the Vienna Basin fossil
Cetacea, Brandt (1873a) introduced a new species
that he questionnably assigned to the genus
Champsodelphis GERVAIS, 1848. Champsodelphis
fuchsii BRANDT, 1873 was based on postcranial
material that came from a brick quarry of Vienna in
1859 (Brandt, 1873a). Brandt (1873a: p. 269)
included in the species 13 other vertebrae from the
Sarmatian of Kishinev (Moldavia), which had been
described previously by Nordmann (1860) as
Delphinus fossilis bessarabicus. Van Beneden &
Gervais (1880) already noted that Brandt’s species is
a synonym of the latter. However, the type material
of D. fossilis bessarabicus is even less diagnostic
than that of C. fuchsii, and thus the complete
taxonomic review of C. fuchsii is problematic. The reinvestigation of the holotype material of D. fossilis
bessarabicus is beyond the scope of the present
study and thus, we use the species name “C.” fuchsii
here.
The Romanian skeletons are assigned to the
species “Champsodelphis” fuchsii on the basis of
their humerus morphology. It is often stated that the
morphology of the postcranial elements including the
humerus provides little phylogenetic information in
the Odontoceti (e.g. Fordyce & Muizon, 2001). Yet,
the likely number of odontocete species in the
Carpathian Basin late Middle Miocene is known, and
moreover it has been surveyed mainly on the basis
of the humerus morphology (Kazár, 2003). Hence,
the morphologic agreement between the humeri of
the Iris Quarry specimens and the holotype of “C.”
fuchsii is regarded here as taxonomically reliable.
The possibility to phylogenetically revise “C.”
fuchsii arose by studying the dolphin material of the
Iris Quarry in Cluj-Napoca.
Although the herein described material contains
in large part the same postcranial elements as does
the holotype (cervical and lumbar vertebrae,
sternum, scapular fragment and humerus), the
tympanic bullae and especially, the periotics of the
MBT material extend our knowledge about the
phylogenetic relations of the species. The periotic
associated with the MBT 15029 skeleton and the
MBT 15001 periotics undoubtedly show affinities with
members of the family Kentriodontidae. The
elongated form of the periotic, the low pars
cochlearis, the narrow, almost slit-like internal
auditory meatus and especially, the placement of the
dorsal angle vs. the ventral angle on the anterior
process indicate close phylogenetic relations with
Atocetus spp.
In diagnosing the genus Atocetus, Muizon
(1988a) emphasised that the dorsal angle of the
anterior process of the periotic is always situated
anterior to the ventral angle in medial view. Two of
the three periotics from the Iris Quarry display this
character state (in MBT 15001/a the corresponding
part of the periotic is broken away), for which it
seems reasonable to questionnably include
“Champsodelphis” fuchsii in the genus Atocetus.
There are other features of the periotic that show
close relationships to Atocetus. Barnes (1985) gives
a list of peculiarities of the periotic of A. nasalis,
which include the presence of a prominent crest on
the posteromedial margin of the internal auditory
meatus and the eminence between the fenestra
rotunda and the perilymphatic foramen. The former
can be observed with one periotic of the Iris Quarry
material, the latter eminence is prominent in all three
periotics of A.(?) fuchsii. The only important
183
E. KAZÁR, M. VREMÍR & V. CODREA
difference between the periotics of A.(?) fuchsii vs. A.
nasalis and A. iquensis is the morphology of the
anterior process, which is larger and has a pointed
tip in Brandt’s species.
More dramatic are the differences of the tympanic
bullae between the Iris Quarry finds and those of A.
nasalis and A. iquensis. The narrowed inner
posterior prominence and the low involucrum of A.(?)
fuchsii is in sharp contrast with the robust bullae and
the bulbous posterior parts of the involucrum in the
North and South American species. It is unknown
whether the different tympanic morphology of A.(?)
fuchsii reflects difference in the hearing abilities of
the species. Studies focusing on the hearing of
odontocetes equivocally indicate that the cochlear
structure is directly connected with hearing (e.g.
Fraser & Purves, 1960; Fleischer, 1976; Ketten,
1992; Luo & Eastman, 1995; Luo & Marsh, 1996),
but little information exists on the differences in the
tympanic morphology of odontocetes on lower
taxonomic level as related to differences in function.
Nummela et al. (1999) concluded that the tympanic
bullae are functionally similar in extant odontocete
taxa in spite of the differences in their morphologies.
If this holds true for the Miocene species of Atocetus,
then different habitats can not account for the
contrast in tympanic morphology between A.(?)
fuchsii and the other two species of the genus.
The humerus morphology varies considerably
between species of the Kentriodontidae (for a short
overview see Kazár & Venczel, 2003). Atocetus
iquensis and A.(?) fuchsii have remarkably similar
humerus morphologies in that their shafts are
extending distally in lateral view. The deltoid
tuberosity is not very prominent but it occupies a
large part of the radial margin, and it almost reaches
the distal epiphysis of the bone in both species. The
only known Middle Miocene form with a similar
morphology
is
another
Carpathian
Basin
kentriodontid (unnamed n. sp. of Kazár & Venczel,
2003). The humerus of A.(?) fuchsii differs from A.
iquensis in the presence of the fovea olecranica. In
the Peruvian species, a complete reduction of the
olecranon process of the ulna can be observed
(Muizon, 1988a). Muizon (1988a) regarded this
feature diagnostic for the genus Atocetus, but in the
light of the newly described material of A.(?) fuchsii it
seems more likely that the reduction of the olecranon
took place only in A. iquensis.
TAPHONOMY
The dolphin material from the Iris Quarry of Cluj
was collected in the 1960s, without taphonomic data
collection. Luckily, during the excavation and
subsequent preparations, most of the skeletal
elements were not removed from the matrix. Figure 9
and 10 of Plate 1 show the skeletal elements of the
MBT 14943 and MBT 15029 specimens in the
calcareous marl slabs. The MBT 15001 ear bones
184
were found ex situ, washed out from the section
close to the site where the skeletons were excavated
(oral communication from Prof. Şuraru Nicolae to V.
Codrea). The left periotic and tympanic, and the right
tympano-periotic complex most likely belonged to a
single individual, indicating that a third skeleton might
have been preserved in the dolphin-bearing layer.
The preserved vertebrae, and most bones of the
left flipper of the MBT 14943 specimen remained in
anatomical articulations. Only the cuneiform of the
carpals is somewhat dislocated, and the distal
phalanges of some fingers are lost. The scapula lies
in its presumed original position, however, the whole
flipper is shifted to close at a smaller than
physiologically normal angle with the main axis of the
scapula. The left flipper is exposed with its medial
surface upward. A few more carpals and phalanges
lie in the vicinity of the left elbow joint, these are most
likely disarticulated elements of the right flipper, just
like the fragmentary right humerus and radius. The
latter elements were found between the arch of the
vertebral column and the left scapula. From the
placement of the flipper elements it can be
concluded that the carcass was lying on its left side
when buried, and that the soft tissues of the chest
and the left flipper completed decomposition after
burial. The right flipper, on the other hand, probably
hung out from the sediment and so its elements
became disarticulated and displaced before burial.
The two possible cranial fragments indicate that the
skull undervent fossilization with the other elements.
The MBT 15029 shows a somewhat different
scenario. Here, all elements are disarticulated and
displaced from their original anatomical positions.
Nevertheless, both tympano-periotic complexes
were preserved in the vicinity of the mandible, the
atlas, axis and the subsequent cervical and
thoracic
vertebrae
are
approximately
in
anatomical sequence. Also, the scapula and the
sternum are partially overlapping, pointing to only
slight displacement of the elements. While the left
periotic and tympanic were probably lost after
excavation (their impressions were clear in the
unprepared slab), the skull is altogether missing
and was possibly not fossilized. In conclusion, the
carcass of the MBT 15029 specimen probably
had became already incomplete before it sunk to
the bottom (? with its skull and posterior parts of
the vertebral column already lost) in a fashion
described by Schäfer (1962). The possibly slow
burial must have followed the decomposition of
the soft tissues.]
PALEOBIOLOGY
Both skeletons (MBT 14943 and MBT 15029)
have completely fused vertebral centra, and the
epiphyses of the preserved arm bones are likewise
ankylosed to the shafts. Thus, both specimens are
considered physically mature. A comparison of the
DOLPHIN REMAINS (CETACEA: ODONTOCETI) FROM THE MIDDLE MIOCENE OF CLUJ-NAPOCA, ROMANIA
elements preserved with both skeletons, notably, the
humeri and some of the thoracic vertebrae, reveals
that the humerus of the MBT 14943 individual was
considerably (20-25%) larger than that of the MBT
15029 (Table 3). The vertebral measures, on the
other hand, do not draw such a clear picture (Table
2). The width and height of the vertebrae are
generally larger in the MBT 14943 specimen,
whereas the centrum lengths are more or less the
same in both specimens or slightly larger in the MBT
15029. These data suggest that in Atocetus(?)
fuchsii either significant intraspecific variation in body
size or sexual dimorphism must be presumed. In a
sexually dimorphic population of the recent
bottlenose dolphin (Tursiops truncatus) the males
possess allometrically larger propulsion features and
weapons (flippers and flukes), which may help them
to coerce females as part of their mating strategy
(Tolley et al., 1995; Connor et al., 2000).
The length reduction of the vertebral centra
accompanied by an increase in the vertebral count is
a tendency of phylogenetic significance, which is
directly correlated with column stability and
swimming style (Howell, 1930; Slijper, 1936;
Buchholtz, 2001). Atocetus(?) fuchsii had slightly
elongated lumbar and posterior thoracic vertebrae,
whereas the contemporaneous A. iquensis (late
Middle to early Late Miocene; Muizon, 1988a) and
the geologically younger A. nasalis (Late Miocene;
Barnes, 1985) had shortened bodies of the thoracic
and lumbar vertebrae. Both A. iquensis and A.
nasalis were more derived in this respect than A.(?)
fuchsii.
The flipper of A.(?) fuchsii shows the general
outline of modern delphinids, however, a number of
differences suggest that the Middle Miocene species
was less specialized (Fig. 2). The humerus, although
progressive among Miocene kentriodontids in its
reduced length and in the distal broadening of the
shaft, is much less robust and compact than the
humerus of present-day delphinids. The gap
between the radius and ulna indicates the remnant of
the antebrachial muscles. The number and overall
morphology of the carpals is the same as in modern
dolphins, but their size, and especially, that of the
lunar is larger than in Tursiops and Stenella. The
carpalia, as a whole, occupy more of the flipper area
than in present-day delphinids. Likewise, the
metacarpals and the phalanges are more elongated
in A.(?) fuchsii. Although the exact number of
phalanges of the fingers II-IV is uncertain, it appears
that hyperphalangy of the fingers II-III was less
pronounced in A.(?) fuchsii than in modern
delphinids such as Tursiops truncatus, whereas the
fingers IV and V were not as reduced in length.
The flipper of Atocetus(?) fuchsii was wider at the
level of the carpals, and probably shorter and less
rigid than the pelvic limb of the pelagic, fast-moving
dolphins of recent days.
Figure 2. Comparison of the forelimbs of the Middle
Miocene Atocetus(?) fuchsii (to the left; based on the MBT
14943 specimen) and the recent Stenella attenuata (to the
right; skeletal parts redrawn after Perrin, 1975). Drawn are
the left forelimbs in medial view. Not to scale. Shaded
area: Supposed outline of the flippers. Black filling:
reconstructed elements. The exact number of phalanges of
fingers II and III of A.(?) fuchsii is unknown and thus, the
outline of its flipper is hypothetical. The supposed
phalanges 2 and 3 of finger IV were dislocated in the MBT
14943 specimen, their exact orientation is reconstructed.
PALEOBIOGEOGRAPHY
Besides the type locality and the Iris Quarry in
Cluj-Napoca, Romania, Atocetus(?) fuchsii has been
reported from a few other localities in the Vienna
Basin and in Hungary (Brandt, 1873a; Kazár, 2003).
However, future taxonomic revision of the species
may possibly extend the fossil record of A.(?) fuchsii
in the Paratethys region. In spite of recent advances
in the study of old and new Miocene delphinoid
material (e.g. Bianucci et al., 1994; Bianucci &
Varola, 1995; Bianucci, 2001; Brocard, 2000), there
is no indication of the species in the Mediterranean
and the Atlantic coasts of Europe. Other members of
the subfamily Pithanodelphinae in Europe are
Pithanodelphis cornutus DU BUS, 1872 from the
Miocene of Antwerp, Belgium (Du Bus, 1872), and
Leptodelphis stavropolitanus KIRPICHNIKOV, 1954
from the Middle Miocene of Moldavia (Kirpichnikov,
1954; Muizon, 1988b). Barnes (1978) suggested that
the Moldavian species Sarmatodelphis moldavicus
185
E. KAZÁR, M. VREMÍR & V. CODREA
KIRPICHNIKOV, 1954 may be another member of
the subfamily. The latter two species, however, are
based on fragmented skulls and are in need of a
taxonomic review.
The closest relatives of A.(?) fuchsii, members of
the genus Atocetus have recorded occurrences from
the Pisco Formation of Peru (Muizon, 1988a) and
from Orange County, California (Barnes, 1985,
1988). More recently, a new species of Atocetus has
been discovered from the Late Miocene of the Chino
Hills, California (Barnes et al., 2003). All these
species were found at the eastern shoreline of the
Pacific Ocean in the north and south hemispheres.
The remains of Atocetus(?) fuchsii in Central Europe
show that the genus was represented in the ancient
sea Paratethys as well, and it must be assumed that
a related species inhabited the Atlantic Ocean and
the Mediterranean, through which the ancestors of
A.(?) fuchsii could enter the Paratethys.
Acknowledgments
The present study greatly benefited from
discussions with Lawrence G. Barnes (Natural
History Museum of Los Angeles County, California),
László Kordos (Geological Institute of Hungary,
Budapest), and Christian de Muizon (MNHN).
Thanks are due to Mikael Fortelius (Museum of
Palaeontology, University of Helsinki), as well as to
Gudrun Höck, Ortwin Schultz (NHMW), Christian de
Muizon (MNHN), David J. Bohaska and Charley W.
Potter (National Museum of Natural History,
Washington D.C.) for facilitating access to
comparative material in their care.
Zoltán Lantos (Geological Research Group of the
Hungarian Academy of Sciences, Budapest) did the
photographs for Figs. 1a and 8 of Plate 1. Partial
funding of the study was provided by the Hungarian
National Science Foundation (No. OTKA-T.31823)
granted to the first author.
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PLATE I
Fig. 1 – MBT 15001/a, left periotic in dorsal view (a) and in ventral view (b). Scale bar for Figs. 1, 2 and 3
equals 1 cm.
Fig. 2 – MBT 15001/b, right tympano-periotic complex in lateral view.
Fig. 3 – MBT 15001/c, left tympanic bulla in medial view (a) and in ventral view (b).
Fig. 4 – MBT 15029, atlas from anterior and slightly dorsal. Scale bar for Figs. 4-7 equals 1.5 cm.
Fig. 5 – MBT 15029, 7th cervical vertebra.
Fig. 6 – MBT 15029, thoracic vertebrae in ? anterior view.
Fig. 7 – MBT 15029, lumbar vertebra in ventral view. Posterior: upwards.
Fig. 8 – MBT 14943, left humerus in anterior view (a) and in lateral view (b). Scale bar: 3 cm.
Fig. 9 – MBT 14943, all preserved skeletal elements in situ. The 10th thoracic vertebra is erroneously placed
in the place of the (missing) 9th thoracic vertebra in the photograph. Diameter of the Nikon lense cap is 5.5
cm.
Fig. 10 – MBT 15029, all preserved skeletal elements in situ. Scale bar: 3 cm.
187
E. KAZÁR, M. VREMÍR & V. CODREA
PLATE I